Broadband ventilated metamaterial silencer for high reflection based on Fano-like interference

Conventional sound shielding structures is difficult to meet the requirements of low-to-middle frequency broadband sound insulation and free ventilation. In this paper, we propose a ventilated metamaterial silencer based on Fano-like interference, which can achieve the sound transmission loss (STL) of more than 10 dB in the range of 516-970 Hz with subwavelength thickness (0.11 lambda) while remains an opening area ratio of 23%. The designed silencer is composed of a large central orifice and four surrounding coiling channels, making the sound waves passing through the two areas generate Fano-like asymmetric transmission spectrum and form efficient reflection to insulate sound coming from various directions. The parametric studies are also carried out to investigate the tunable acoustic performance. Experiment measurement matches well with the simulation results. In the future, the proposed silencer may have potential applications in practical environments requiring broadband sound insulation and free air flows.